DE2834387C3 - Electro-optical time display device - Google Patents

Abstract

An electro-optical time-indicating system displays the time by simulating a clock using dial hands. The electrodes of a liquid crystal display are formed by radial track segments and the backing electrodes are subdivided into inner and outer electrodes. The driving of the track segments to indicate hours, minutes and seconds is accomplished by a time division multiplex technique. In order to keep the number of electrode terminals for the track segments to a minimum, the track segments are combined into L track segment cascades with L input terminals. The track segments are arranged in K twin sets such that, as viewed in the clockwise direction, an nth track segment (where n ranges from 1 to L) of one set of the twin sets is always connected with the L+1-nth track segment of the other set of a twin set. The inner backing electrodes are subdivided into M inner blocks with one terminal each, and the outer backing electrodes are divided into N outer blocks with one terminal each. Each twin set is covered by two adjacent inner blocks and two adjacent outer blocks. The time-functional drive of the terminals of the track segment cascades takes place alternatingly in ascending and in descending order, and successive terminals of the inner and outer blocks are energized in a clockwise direction after every change-over between ascending and descending drive.

Description

The invention relates to an electro-optical time display device according to the preamble of claim 1.

Such a display device is described in the German patent application which led to DE-OS 28 20 326. Radially subdivided transparent strip segment electrodes are formed on one side of the electrically influenceable optical material, and on the opposite side, facing away from the viewing direction, counter-electrodes in the form of electrically isolated, concentrically arranged and different radial extensions of circular arcs, the respective peripheral extension of which is a Group of the strip segments formed over it is assigned. Each group has an equal number of stripe segments. The strip segments are connected in series via electrical conductor tracks in such a way that the strip segments of one group are connected in increasing counting order with the strip segments of the peripherally adjacent group in descending order and with those of the next but one group in increasing counting order, and so on, so that above the display material there are as many lines of conductors running alternately inwards and outwards from group to group, i.e. arc-shaped-meandering, as there are strip electrodes assigned to a group without crossing points in the connecting wiring and without more connection poles being required, al? occur in a group of strip electrodes. This makes it possible to realize these circuit connections in a single-layer printed circuit and to connect the integrated circuit for the display control directly to the electrically activatable optical display material; unc ¹ that also enables additional connections for further information displays, for example for displaying time-derived variables such as calendar information, to be accommodated on the edge of such a compact chip, even with a spatially small structure of the display device. A multiplex control circuit is provided for the analog clock-like time display, which uses frequency dividers and counters to determine the current seconds, minutes and hours information from the time base, e.g. To control the counter-electrode lying in a circle segment, and also the affected strip-segment electrode from the group of strip-segments determined by the counter-electrode. With regard to the electrical selection control of the respective stripe segment concerned, the task takes into account that during the transition from one group to the next, due to the meander-

Wiring-related opposing assignment, an inversion must be provided so that not in groups opposite display progression occurs for the implementation of the obtained by means of the counter current time information in the Polarkoo.-dinaten-time representation with the presentation of the spokes, binary coded decimal information is made available and queried in time-division multiplex, in order to then convert them into Control information based on sixty, taking into account that to be guaranteed in groups Inversion, to convert and then to feed a driver circuit with it. About any Multiplex control of the display elements connected downstream of the driver circuit is not implemented Rather, the activation of the electrode pairs required for displaying the current time information takes place or electrode triples apparently time-sequential according to the scanning of the binary encoded counter output information. Due to the dynamic behavior of the visual display material, especially if it is a liquid crystal! with the rotating cell function, problems arise with regard to the desirable display contrast, if the scanning control rate is so high is selected that in addition to the hours and minutes display also a running seconds display is also possible is a disadvantage of this proposed solution that due to the radial non-subdivided, spoke-shaped strip segments and due to the azimuthally non-subdivided group counter-electrode blocks a further deterioration in the required display clarity as a result of overlapping phenomena at the symbol interfaces.

This display device proposed in the earlier application is intended to be a further development of the same generic type Represent display device according to DE-AS 24 51 057, in which for the same time information presentation the same electrode design is selected; but without series interconnection of strip segment electrodes assigned to one another in groups, that is to say with the result that due to the extremely high number of individually implemented connection poles the desirable compact circuit structure - for example for the installation of such a display device in a watch case - is no longer realizable, but at least the realization of the display of additional time-derived Information is prevented. In addition, there is the great susceptibility to errors of those that have to be wired individually Terminal poles compared to wiring formation in printed circuit technology.

In view of the known problem, liquid crystal display elements in dynamic multiplex operation to control is in the patent application, dip led to DE-OS 28 03 899, also for one of the time display corresponding to electromechanical analogue display with spoke azimuth display of Seconds, minutes and hours an electrode formation and interconnection according to the opening suggested earlier registration. To a control circuit for time-dependent electrode control is not discussed in more detail, only the use of four rectangular actuators AC voltages, two of which are identical but phase shifted by 180 ° from one another, suggested.

From the article "Multiplexing Liquid Crystal Displays" by Paul Smith, ELECTRONICS issue 11, 1978, May 25, 78, p. 113/116 ff, it is known to overcome the dynamic problems in the Liquid crystal display cell a multiplex control in the manner of a matrix addressing of display elements to carry out by means of square-wave voltage lines, the selected or for the current Display of electrodes not required to be applied. The voltage difference between assigned Electrodes, i.e. at coordinate intersection points, determine whether a display element is activated here will, or not, on the dimensioning of the square-wave voltage curves to adapt to certain display problems will not be received.

From DE-OS 25 51 542 one of the present generic display device is known in which a selection from the existing strip segment electrodes according to the series connection explained at the beginning is merged. It is controlled by a time-keeping oscillator circuit up-down counter clocked via a divider circuit, which counts as many in each counting direction Has counting positions, as strip segment electrodes are combined to form a group then to reverse the direction and at the same time an up counter to control the counter electrode the next group to advance one step. This progression of the minute display becomes every quarter of an hour a signal for clocking a further up / down counter is derived, which displays the hour controls. But that means that the hour display jumps every quarter of an hour, which is not the usual and corresponds to the desired analog time display; in addition, no continuous seconds display is provided, and the display itself does not take place in multiplex mode, so it results in particular in the case of Use of liquid crystal display elements does not provide the desirable continuous analog time display impression.

The invention is based on the object of providing a display device of the type cited at the beginning continue to train that they while maintaining the advantages, with few connection poles with single layer Wiring to provide a continuous analog time display of seconds, minutes and hours too can achieve an improved display quality with comparatively little additional effort.

This object is achieved according to the invention in that in a display device according to the preamble of claim 1, the measures according to the characterizing part of claim 1 taken will.

For the time display known as such, a modification of the electrode control known as such is required, via a combination of an up / down counter with an up counter, with the formation of this control in accordance with the matrix addressing known as such for a Multiplex display control taken, for which because of only three AC trains required (of which two are identical, just out of phase with each other) and because of the immediate Deriving all time information from a counter chain with only a minimum of additional circuitry effort for clear information display even when using liquid crystal display elements is required.

In the interest of further increased display contrast

expediently acts this modified time-division display control on electrodes that in the radial direction or in the azimuthal direction for geometrically exact delimitation of the symbol representations are subdivided, resulting in clear spoke or partial spoke representations.

The invention is preferred below with reference to one shown in the drawing Embodiment explained in more detail. It shows

Fig. 1 shows the upper, spoke-shaped transparent electrodes carrying board of an electro-optical Liquid crystal time display device according to the invention,

F i g. 2 the associated lower board,

3 shows a block diagram for time determination and display control,

Fig. 4 for the multiplex display control used three square wave alternating voltages,

5 shows two control examples using the control voltages according to FIG. 4 and

Fig. 6 shows an example of the time display on the display device according to FIG. 1 to F i g. 3.

In the illustrated embodiment, spokes extend on an upper plate 1 60 spoke segments 51 to 560 arranged in a circle, each of which is due to its radial subdivision consists of an outer section 2 and an inner section 3. These strip segments 5 are Electrodes of a liquid crystal body as an electro-optical display material, which is located between the upper jo Board 1 and a lower board 4 (see. Fig.2) is. Correspondingly arranged counter-electrodes are provided on the lower plate 4. The strip segment sections 2 and 3 are transparent in a manner known per se.

The strip segments 51 to 560 are combined in ten strip segment series connections. The strip segments S1, 520, 521, 540, 541 and 560 are electrically connected in series in the first strip segment series connection. A connection pole A 1 is provided to control this series connection of strip segments. The connecting lines of the strip segment series connections are laid in a meandering manner. The same applies to the further strip segment series connections. In Fig. 1, the connection poles of the further strip segment series connections are designated by A 2 to A 10. The counter-electrodes arranged on the lower plate 4 are divided into six inner blocks S 1 to S 6 and six outer blocks B 7 to B 12. For each of the blocks Bl to fJ12 such a connection pole 11 to Λ 22 is provided.

The strip segments 51 to 510 and 511 to 520 and 521 to 530 and 531 to 540 and 541 to 550 and 551 to 560 are arranged in groups. The outer strip segment sections 2 of a group each lie above an outer block. The inner strip segment sections 3 of a group overlie an inner block. The strip segment groups 51 to 510 and 511 to 520 or 521 to 530 and 531 to 540 or 541 to 550 and 551 to 560 each form a feo double group, with the first, second to tenth strip segment of one group of a double group viewed clockwise is electrically connected to the tenth, ninth to first strip segments of the other group of the double group. Each double group covers two adjacent inner blocks and two adjacent outer blocks. For example, the double group of the strip segments 51 to 520 lies above the inner blocks B 1 and B 2 and the outer blocks B 7 and B 8.

For example, the first strip segments of the groups are not located at the connection pole A 1, but instead the first and last strip segments from the successive groups alternate, namely the strip segments 51, 520, 521, 540, 541 and 560. The same applies to the other connection poles A 2 to A 10. As shown in FIG. 1, the meandering connection of the strip segments 51 to 560 avoids crossing points of the connecting lines.

The connections Λ 11 to A 22 of the circuit board 4 are contacted on the circuit board 1 via contact pieces not shown in detail. For the electrical connection of the counter-electrodes of the board 4, the connecting poles A 11 'to A 22' are provided on the board 1. As a result, the connection of the electrodes and the counter-electrodes can be achieved solely by contacting the circuit board 1 with the circuit shown in FIG. 3 take place in more detail shown circuit arrangement.

In addition, the circuit boards 1 and 4 have electrode segments 5 for a date display and electrode segments 6 intended for a weekday display.

From the described arrangement of the electrodes and counter-electrodes it can be seen that the liquid crystal body located between the circuit boards can be used for display with only twenty-two connections in the area of each individual strip segment 51 to 560 or their strip segment sections 2 or 3. An hour display is achieved by a corresponding voltage between the relevant connection of the connections A 1 to A 10 of the strip segment series connections and the relevant connection A 11 to A 16 of the inner blocks. A minute display is achieved by a voltage between the connections Λ 1 to Λ 10 and AU, A 17 to A 16, A 22. A seconds display appears at a corresponding voltage between the connections A 1 to A 10 and the connections A Y1 to A 22 of the outer blocks B 7 to B 12.

In this way, for example in FIG. 6 the time:
2 o'clock, 25 minutes and 30 seconds are displayed.

With a cyclical, time-dependent control of the connection poles A 1 to A 10, a display corresponding to the movement of a clock could not be achieved. To avoid this difficulty, the connection poles A \ to / 4 10 are driven alternately in ascending order, ie from A 1 to A 10, and in descending order, ie from A 10 to A 1. According to FIG. 3, forward-backward counters are used for this purpose. The connection poles 11 to Λ 16 of the inner blocks Bl to B 6 and the connection poles A 17 to A 22 of the outer blocks B7 to B 12 are continuously switched on after each change from ascending to descending control of the connection poles Λ 11 to A 10 and vice versa

According to FIG. 3, a display control circuit 7 is connected upstream of the connections A 1 to A 10 and AW to A 22 ′ , which in particular the 4 and 5 generated signals explained in more detail- Before the display control circuit 7 there is a time data takeover and forwarding logic 8 which is controlled by a multiplex device 9 and to which the time data for the second, minute and hour are present. The multiplex device 9 is provided because hours, minutes and seconds are not to be displayed one after the other, but for the user at the same time.

In known manner, the frequency of a time base 10, such as a quartz over divider stages 11 to 1 Hz is divided with this 1-Hz frequency, a 10-up-down counter 12 is acted upon, which acts in such a way to the terminal poles A 1 to A 10, that it alternately switches through the connection poles A 1 to A 10 forwards and A 10 to A 1 backwards. With each reversal of the up-down counter 12, a 6-up up counter 13 is incremented by one digit. This acts on the outer blocks Bl to S12. Controlled by the multiplexing device 9, a seconds display which advances from second to second in a clockwise direction takes place.

The up counter 13 is followed by a further 10 up / down counter 14, which works in the same way as the up / down counter 12, but serves to display the minutes. The up-down counter 14 is followed by a further 6-up up counter 15. This acts simultaneously on the inner blocks B \ to B6 and the outer blocks Bl to B 12. Depending on the multiplexing means 9 thus takes place an encircling manner of a minute hand minutes display.

The up / down counter 14 is also followed by a 1:12 divider 16, which controls a further 10 up / down counter 17 for the hour display.This also switches the connections Λ 1 to Λ 10 or A 10 to A 1 in the manner described The up / down counter 17 switches a further 6 up counter 18 by one step with each reversal, which acts on the inner blocks Sl to B 6 so that, depending on the multiplexing device 9, the counters 17 and 18 continuously display the hour clockwise The hour display is not limited to full hours but also shows intermediate values.

In addition, there is an adjusting device 19 for adjustment the time provided.

The display control circuit 7 can output the signals shown in FIG. The signal a is passed to the terminals A 1 to A 10 controlled by the time data transfer and transfer logic 8. The signal b is passed to the controlled inputs Λ II 'to A 22', ie the relevant inner or outer blocks Signal c is used to act on the non-activated connection poles of the inner blocks, outer blocks and strip segment groups. The frequency of the signals a, b and c is the same and is, for example, twice the frequency of the multiplex device 9.

Signals b and c have the same shape but are out of phase.

An example of a control is shown in FIG. In this case, line I shows the voltage profile at one of the inputs Λ 1 to Λ 10 and line II shows the voltage profile on the strip segment for the inner block and outer block assigned to the desired display. Line II shows the voltage thus occurring on the liquid crystal body, the differential voltage between lines I and II becoming effective on the liquid crystal body. Up to a point in time 11 , the stripe segment in the example is not activated. The voltage curve c according to FIG. 4 is due to him. The stress curve c is also on the assigned inner block and outer block. According to line III, there is no display on the liquid crystal body in the area of this segment.

After the time point 1 1 the strip segment is driven, whereby the voltage waveform present at a him. The assigned inner block is not activated, so that only half the total voltage occurs on the liquid crystal body and the strip segment section in question does not appear. However, the outer block is activated with the signal b. This has the consequence that the full operating voltage occurs on the outer strip segment section, so that it becomes visible.

The desired controls of the Liquid crystal body for practically simultaneous and clockwise progressing hours, minutes and seconds display.

Numerous other exemplary embodiments lie within the scope of the invention. For example, it is possible to provide a different number M or N of inner blocks or outer blocks and a different number L of strip segment series connections. The division will be chosen so that the product of L + M is equal to the number of the intended strip segments. The sum L + M + N gives the number of necessary connections. If, for example, a combination of twenty strip segments each is selected to form a strip segment series connection, then three inner blocks and three outer blocks are to be provided for a total of sixty strip segments. In this case, twenty-six connections are required for control. Counters 5 to 18 must then also be designed accordingly.

For this purpose 5 sheets of drawings 130 216/304

Claims (2)

Patent claims: 1. Electro-optical time display device with analog information of the time in hours, minutes and seconds in the manner of a pointer clock, in particular by means of a liquid crystal display device, the display device peripherally adjacent groups of radially extending strip segments with assignment of the total -Strip segments for minute display, an inner strip segment section for hour display and an outer strip segment section for second display and corresponding to the strip segment section subdivision in inner and outer blocks has counter-electrode blocks, of which two peripherally adjacent inner blocks including these radially assigned outer blocks cover a double group of Lwei peripherally adjacent strip segment groups, with strip segments, specifically one strip segment of a group, being interconnected in such an assignment that meandering paths in Re Starting from the first stripe segment of the first group over the last stripe segment of the second group and so on over the first and the last stripe segment of the peripherally adjoining double group of stripe segments - and this accordingly also for the other stripe elements of the groups - are given, whereby a The end of each of these series connections lead to a strip segment connection pole and each of the counter-electrode inner and outer blocks each lead to a further connection pole, and a time-division control circuit with second, minute and hour counters operated from a time base via a divider stage the connection poles are connected in that the connection poles of the counter-electrode blocks, according to their peripherally adjacent order, one after the other, the connection poles of the strip segments, however, are controlled again in reverse order with each block change, characterized in that the counters than when counting End switching up / down counters (12,14,17) with as many counting steps as one block (B) strip segments · (S; 2-3), each followed by an up counter (13; 15; 18) with as many counting steps as the counter electrode blocks (B) are formed, and that the successively appearing up / down counter output signals and the successively appearing up-counter output signals via a three-signal mulliplex circuit (coupling logic 8 with multiplex circuit 9) to control the strip segment connection poles ( A 1 ... A 10) to be controlled according to the current time display with a binary square wave or the to be controlled according to the current time display Control the counter-electrode block connection poles (A 11 ... A 16, / 117 ... A 22) with a trinary step oscillation and the connection poles (A 1 ... Λ 22) not activated for the current time display with an identical but phase-shifted step oscillation . 2. Display device according to claim 1, characterized in that the strip segments (S) corresponding to the radial subdivision of the opposing Electrode blocks (B) are divided radially into inner and outer blocks but are electrically connected in series and that the counter-electrode blocks (B) are subdivided peripherally according to the peripheral delimitation of adjacent strip segments ßy but in groups to form the inner and outer blocks (B) are electrically interconnected.